Some Trilobites of the Cincinnatian
by Rich Fuchs, Dry Dredgers

Trilobites are extinct members of the Arthropod family which were quite
common in the Paleozoic sea waters that covered what is now the area in and
around Cincinnati, Ohio. Fossils of these creatures, although plentiful, are
sometimes hard to find. But persistent looking can lead to great
"treasures" and, once in a while, pockets of these long-gone
creatures.

Although only a couple of species are very common in the area,
about 18 species of trilobites have been found in the limestones and shales of
the region. This home page is designed to acquaint you with some of the more
common, and a few of the less common, members of the trilobite family of the
Ordovician Period of Cincinnati history.

Achatella carleyi: a rare trilobite. The
exoskeleton is somewhat flattened with very prominent compound eyes. Usually
found in the Fairview Formation.

Acidaspis cincinnatiensis: a spiny trilobite.
Rarely found complete, pieces can be found in many rocks from the Kope up into
the Maysville. Cephalon contains a characteristic occipital spine extending over
the thorax. Generally of very small size, but some specimens measuring several
centimeters have been found. Click here for a photo
of Acidaspis

Cryptolithus bellulus: the "laced-collar" trilobite
of the Kope Formation. Cephalons and parts of cephalons are readily found.
However, complete skeletons are difficult to find because the thoracic segments
are very thin and fragile. Identification of Cryptolithus
fragments

Flexicalymene meeki: the most common trilobite of the
Cincinnatian. Pieces, as well as complete specimens, can be found in nearly all
rock formations above the Kope. Other species include F. retrorsa, not
pictured.

Flexicalymene granulosa: a smaller version of F. meeki,
found in the Kope. The skeleton is covered with little bumps. Hence, the species
name.

Isotelus maximus: the largest trilobite of the area. Complete
specimens up to 40 cm. in length have been found. Pieces collected indicate that
some grew to as much as 60 cm. (24 inches) or more. This is the official Ohio
state fossil.

Primaspis crosotus (suspected by some to be Meadowtownella crosotus):
another small, rare trilobite, similar to Acidaspis, but without the
occipital spine. Pieces are found in some rocks. Limited to the lower portions
of the Kope Formation.

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